It has been shown in years of experimental work that the visual system of the primate is far more extensive than was long thought to be the case. Studies employing the effects of lesions, the responses of single cells, and anatomic methods have shown that a cortical visual pathway extends forward, well beyond the prestriate region, in the inferior portion of the temporal lobe. This extensive cortical system appears to process visual stimuli with serial increments in complexity as impulses cascade forward from the striate cortex. Some evidence has accrued that impulses then enter the limbic system via the amygdala and that in this part of the brain the visual stimuli receive motivational value. In view of the previously demonstrated ability of the 2-deoxyglucose method to map functional visual pathways (e.g., to demonstrate the ocular dominance columns, the orientation columns, the cortical locus of the blind spot of the retina) it was thought that it might be possible to map this extended visual system in detail and therefore the present collaboration was undertaken. In a series of experiments in which one hemisphere of a monkey's brain was deprived of visual stimuli by surgical section of one optic tract and the forebrain commissures it was indeed possible to demonstrate in exquisite detail the extent of this large region of visually responsive cortex. The results were reported at the recent meetings of the American Academy of Neurology (abstract, 1978). In the presentation, color coding of autoradiographs permitted the depiction of differences in rates of local glucose utilization in all areas of a coronal section simultaneously. This provided a unique amalgamation of anatomic, physiologic and biochemical information in a single picture. It marked the limits of the visual cortical analyzer in detail (notably within brain sulci) and also marked zones within the limbic system which can be activated by visual input. Plans are underway to study other sensory systems (auditory and somatosensory) in a similar manner to test the hypothesis that other portions of the temporal lobe may be similarly involved in processing these modalities.